How to find the rare disease zebra behind you

If you hear hooves behind you, don’t turn around and expect to find a zebra. It’s an old adage, essentially meaning that common diseases are common and rare diseases are rare.

But if you’re a medical professional working in the field of rare diseases, the zebra is exactly what you want to find.

When diagnosing a patient who is ‘tired all the time’, you might first think of anaemia, or low mood, stress, or hypothyroidism. The list of common causes is very long. But what if the diagnosis is none of these? What if the case is particularly difficult? How does the medical professional hunt down the zebra?

FindZebra is a search engine for rare diseases – and carries a warning that it is a research project only to be used by medical professionals. “Rare diseases are especially difficult to diagnose and this online medical search engines comes in support of medical personnel looking for diagnostic hypotheses,” says the FindZebra website.

If I consult Dr. Google about being tired all the time, this brings up the common causes. But a search for tired all the time on FindZebra brings up some rather more obscure examples. Alexion’s stomping ground of paroxysmal nocturnal haemoglobinuria is first, followed by idiopathic pulmonary haemosiderosis, and Legg-Calve-Perthes syndrome a bit further down the list. The search engine indexes over 31,000 documents covering rare diseases, and gives the professional information about the disease and a link to further information. It’s a very clever idea, and could indeed be very helpful “when the equine turns out to be a zebra.”

Do you think this search engine a useful tool that will make the diagnosis of rare diseases easier, or is it just a hypochondriac’s nightmare?